Correct exposure annunciator circuit

ABSTRACT

A switching means connects a light annunciator with a voltage source. The annunciator indicates that a scene has been sufficiently illuminated to properly expose a light sensitive film of an associated camera. The switching means is responsive to the operation of a light quenching means of a computer-flash system for providing an effective contact closure thereby energizing the annunicator. The switching means is then responsive to a manual switch opening or a subsequent operation of a light flashing means of the computer-flash system, for opening the switching means and de-energizing the annunciator.

United States Patent Wilwerding [54] CORRECT EXPOSURE ANNUNCIATORCIRCUIT [72] Inventor: Dennis J. Wilwerding, Littleton,

Colo.

[73] Assignee: Honeywell Inc., Minneapolis, Minn.

[22] Filed: Jan. 28, 1971 [21] Appl. No.: 110,700

[52] US. Cl. ..315/158, 307/252 A, 307/252 .1,

[51] Int. Cl. ..H05b 41/36 [58] Field of Search ..307/252 A, 252 J, 311;

[56] References Cited UNITED STATES PATENTS 3,601,652 8/1971 Burnett..315/156 3,541,387 ll/l970 Ackermann.....

3,524,986 8/1970 Hamden 10/1965 Billings ..307/252 .1 4/1969 Skiruin..315/149 Primary Examiner-John Zazworsky Attorney-Arthur l-l. Swansonand Lockwood D. Burton [57] 1 ABSTRACT 23 Claims, 3 Drawing FiguresPATENTED DEC 1 9 m2 SHEET 1 [IF 2 FIG. 2

INVENTOR. DENNIS J. WILWERDING BY i f ATTORNEY.

CORRECT EXPOSURE ANNUNCIATOR CIRCUIT The present invention relatesgenerally to computerfiash systems, and more particularly to a correctexposure annunicator circuit for use with computer-flash systems.

Computer-flash systems have been provided wherein a light producingmeans is actuated to illuminate a scene to be photographed. A lightsensing means detects the scene illumination and actuates a lightquenching means when sufficient light has been produced to properlyexpose a light sensitive film of an associated camera means.I-Ieretofore, meters have been provided whereby a photographer reads avalue of the existing light level from a meter and then takes thepicture if the existing light level, as read, is sufficient. A change inthe light level which occurs after the light meter has been read, butbefore the picture was taken, may result in an improperly exposedpicture. The photographer, however, will not be aware of the film beingimproperly exposed until a later time when the film is developed. Inmany cases, the scene being photographed is an impromptu scene whichcannot be created at a later time. When light conditions are less thanideal, and supplemental light producing devices are required, theproblem becomes more pronounced since light meters are of no help.Therefore, there has existed a need for a means of indicating to aphotographer, immediately after taking a picture, that a scene beingphotographed has been sufficiently illuminated to properly expose alight sensitive film of a camera. In

some computer-flash photographic systems, the light.

quenching means is a gas discharge tube during the operation of which anincidental light is emitted. That incidental light is normally confinedto the immediate area of the quench tube. Some prior art devices haveused that incidental light as an indication to a photographer that therehas been sufficient light provided for proper exposure of a film, to ascene being photographed. Since the duration of the incidental lightemitted by the light quenching tube is very brief, that momentaryindication is very likely to occur and not be noticed by thephotographer.

It is therefore an object of the present invention to provide animproved illumination sufficiency indicator.

It is another object of the present invention to provide an annunicatorcircuit for indicating that a scene being photographed has beensufficiently illuminated to properly expose a light sensitive film of anassociated camera means.

It is a further object of the present invention to provide anannunciator circuit for providing a lasting indication that correctexposure has been attained.

It is a still further object of the present invention to provide anannunciator circuit wherein a correct exposure indication may beselectively terminated by a photographer.

It is yet another object of the present invention to provide a correctexposure indicator which is automatically terminated when a subsequentphotographic cycle is initiated.

In accordance with these and other objects, there has been provided, inaccordance with the present invention, a light emitting indicator, orcorrect exposure annunciator, connected to a voltage source by aswitching means. The switching means is responsive to the operation of aquench circuit of a computer-flash system for providing an effectivecontact closure whereby the annunciator is energized. The switchingmeans is then responsive to either a subsequent operation of a lightproducing means of the computer-flash system, or a selectively operablereset switch, for effectively opening the effective contact closure,whereby the annunciator is de-energized and made ready for the nextoperation.

A better understanding of the present invention may be had from thefollowing detailed description when read in connection with theaccompanying drawings, wherein:

FIG. 1 is a schematic diagram illustrating one embodiment of the presentinvention.

FIG. 2 is a schematic diagram illustrating a second embodiment of thepresent invention.

FIG. 3 is a schematic diagram of a computer-flash circuit. I

Referring in detail to FIG. 1-, there are shown four input terminals 1,3, 5 and 7. A battery 2 is shown in phantom connecting the terminals 1and 7. A series circuit comprising a manual switch 9, a light indicatoror annunciator 11, a resistor 14, and a capacitor 15 connect theterminal 1 with the terminal 3. The junction between the resistor 14 andthe capacitor 15 is connected to the anode of a silicon controlledrectifier (SCR) 18. A resistor 19 connects the gate and cathodeterminals of the SCR 18. A capacitor 21 connects the gate terminal ofthe SCR 18 with the input terminal 5. The cathode terminal of the SCR 18is connected to the input terminal 7.

In computer-flash photographic systems, a first control signal isgenerated which effects the operation of light producing means.Subsequently, a second control signal is generated which is indicativeof the operation of a light quenching means operative to effectivelyterminate the light given off by the light producing means. Thegeneration of the second control signal is initiated by. a light sensingmeans when sufficient light has been produced by the light producingmeans to sufficiently illuminate a scene being photographed to properlyexpose a light sensitive film in a camera. Therefore, the generation ofthe second control signal is a positive indication that a scene beingphotographed has been sufficiently illuminated to properly expose thefilm in a camera. For example, in US. Pat. No. 3,519,879 to Francis T.Ogawa, which is assigned to the Assignee of the present invention andincluded herein by references the light producing means is a flash tube4 in FIG. 1 of the Ogawa patent; the first control signal is a suddenvoltage decrease appearing at the point 13 therein when the switch 12 isactuated. The light quenching means shown by Ogawa as the quench tube 37and the second control signal as sudden voltage change appearing at thepoint 25 when his light activated silicon controlled rectifier 17becomes conductive. For the sake of convenience, FIG. 1 of the abovereferenced Ogawa patent has been partially reproduced and shown as FIG.3 herein. In the operation of the present invention, the terminals 1 and7 are connected across a voltage source or battery 2 shown in phantom.The terminal 3 is connected to a point in a photographic flash controlcircuit at which appears the first control signal, such as point 13 inFIG. 3. The input terminal 5 of FIG. 1 is connected to a point at whichappears the second control signal, such as point 25 in FIG. 3. Theswitch 9 of FIG. 1 is closed when a photographer is ready to take apicture. The SCR 18 will then be nonconductive or open. Since the SCR 18is open, the light indicator or annunciator 11 will be off. A firstcontrol signal indicative of the operation of a light producing meanswill appear at the input terminal 3 followed by the appearance of asecond control signal at the input terminal 5, indicative of theoperation of a light quenching means which effectively terminates thelight given off by the light producing means. The second control signalappears in the form of a ringing signal, in the present example,appearing at the terminal 5. That ringing signal is coupled through thecapacitor 21 to thegate terminal of the SCR 18. The positive goingportion of the ringing second control signal renders the SCR l8conductive. With the SCR 18 conductive, a circuit including the lightindicator 11 is established between the terminals 1 and 7 across whichthe voltage source 2 is connected. Therefore, when the light indicatorgoes on, it signifies the correct exposure has been obtained, since thelight quenching operation has been initiated. The correct exposureindicator or annunciator 11 will remain on until it has either beenrecognized by the photographer and the switch 9 is opened, or anotherpicture taking cycle is begun as indicated by the appearance of a firstcontrol signal at the input terminal 3. That signal which is a momentarynegative going pulse in the present example, will be coupled through thecapacitor 15 to the anode of the SCR 18 thereby rendering the SCR 18nonconductive and opening the light indicator circuit. It is understoodthat the switch 9 may be omitted from the circuit shown in FIG. 1, withthe result that the correct exposure indicator would be turned off onlyby a subsequent first control signal indicative of a subsequentoperation of the light producing means. Alternatively the input terminal3 and the capacitor 15 may be omitted, and the correct exposureindicator or annunciator 11, once turned on by the appearance of asecond control signal indicative of the operation of a light quenchingmeans, will be turned off, solely by the opening of the switch 9 by thephotographer.

In FIG. 2 there are shown three input terminals, 23, 26 and 27. Abattery 24 is shown in phantom connecting the terminals 23 and 27. Aseries circuit comprising a switch 29, a light indicator 30, a resistor31, and a capacitor 32 connects the input terminal 23 with the terminal26. The junction between the resistor 31 and the capacitor 32 isconnected tothe anode terminal of a light activated silicon controlledrectifier (LASCR) 33. A resistor 35 connects the input terminal 27 tothe gate terminal of the LASCR 33. The cathode terminal of the LASCR 33is connected directly to the input terminal 27. A light quenching tube37 is also shown with three electrodes 38, 39 and 40. The electrodes ofthe quench tube 37 are numbered and connected in the computer-flashcircuit as shown in the above referenced patent of Francis T. Ogawa andFIG. 3 herein. The LASCR 33 arranged to be relatively close proximity tothe quench tube 37. Since the quench tube 37 is a gas discharge tube, anincidental light is emitted therefrom during the conduction thereof.That incidental light represents the second control signal in theexamplary embodiment shown in FIG. 2. LASCR 33 is arranged to detect andrespond to that incidental light as an indication that the quench tube37 has,indeed, fired and the light terminating operation of acomputer-flash system has been effected. As hereinbefore mentioned, theoperation of the quench tube 37 is also indicative of the fact that ascene being photographed has been sufficiently illuminated to properlyexpose a film in an associated camera. When a photographer is ready totake a picture, the switch 29 is closed. A first control signal issubsequently generated when the light producing operation has begun.After sufiicient illumination has been received by a sensing means, asmore fully explained in the referenced patent, the second control signalis generated which triggers the operation of the quench tube 37. Thequench tube 37 will then emit an incidental light or second controlsignal when it becomes conductive. That incidental light is detected bythe LASCR 33 and a current will be initiated from the gate terminal ofthe LASCR 33 through the resistor 35. That current will forward bias thegate-cathode junction of the LASCR 33, turning on the LASCR. A voltagesource or battery 24, is normally connected between the input terminals23 and 27; the input terminal 26 is connected to a point in a computerflash circuit at which appears a first control signal representing theoperation of a light producing means such as point 25 of the referencedOgawa patent as shown in FIG. 3 herein. When the LASCR 33 becomesconductive, a circuit is established including the voltage sourceappearing'across the terminals 23 and 27 and the correct exposureindicator 30. The correct exposure indicator or annunciator 30 will thenbe turned on and will remain on until the'photographer has recognizedthe indication and opened the switch 29 or the appearance of asubsequent first control signal at the terminal 26. As hereinbeforeexplained, the first control signal is in the form of a sudden decreasein voltage in the present example. When that sudden decrease in voltageappears at the terminal 26, it is coupled through the capacitor 32 tothe anode terminal of the LASCR 33. The LASCR anode terminalvoltagethereupon drops below its threshold voltage and the LASCR 33 will becomenonconductive. It will understood that either the switch 29 or thecapacitor 32 may be omitted from the circuit which would give similarresults as the omission of the switch 9 or the capacitor 15 of FIG. 1.

Thus there has been provided in accordance with the present invention, acorrect exposure annunciator circuit for use in combination with acomputer flash system which provides a selectively terminable orautomatically terminable indication to a photographer that a lightsensitive film of a camera has been sufficiently exposed to a scenebeing photographed.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows: Y

1. An annunciator circuit for use with a photographic circuit, saidphotographic circuit including a first signal generating means forgenerating a first control signal, a second signal generating means forgenerating a second control signal, a light producing means responsiveto said first control signal for initiating the operation of said lightproducing means whereby light is emitted therefrom, and a lightquenching means responsive to l060ll 0630 said second control signal forinitiating the operation of said light quenching means whereby saidemitted light is effectively terminated,

said annunciator circuit comprising:

a signal responsive annunciator indicator,

a control member serially connected in an energization circuit with saidannunciator indicator,

said control member being responsive to said second control signal toeffect a closure of said energization circuit, thereby activating saidannunciator indicator, and

selectively operable means for subsequently interrupting saidenergization circuit. I

2. The invention as set forth in claim 1 wherein said control member isa light activated silicon controlled rectifier (LASCR), having itsanode-cathode path serially connected in said annunciator circuit, saidLASCR being arranged in proximity ti said light quenching means wherebyto render said LASCR conductive in response to light given off during anoperation of said light quenching means.

3. The invention as set forth in claim 1 wherein said control membercomprises a silicon controlled rectifier (SCR) having its anode-cathodepath serially connected in said annunciator circuit and means forconnecting the gate electrode thereof to said second signal generatingmeans whereby to render said SCR conductive in response to said secondcontrol signal.

4. The invention as set forth in claim 3 wherein said annunciatorindicator is a lamp member.

5. The invention as set forth in claim 3 wherein said selectivelyoperable means is a manually operated switch means serially connected insaid energization circuit, a momentary selective operation of whichinterrupts said energization circuit, rendering said SCR nonconductive.

6. The invention as set forth in claim 3 wherein said selectivelyoperable means comprises means for connecting said first signalgenerating means to the anode of said SCR whereby to render said SCRnonconductive in response to said first control signal.

7. The invention as set forth in claim 2 whereinsaid annunciatorindicator is a lamp member.

3. The invention as set forth in claim 2 wherein said selectivelyoperable means is a manually operated switch means serially connected insaid energization circuit, a momentary selective operation of whichinterrupts said energization circuit, rendering said SCR nonconductive.

9. The invention as set forth in claim 2 wherein said selectivelyoperable means comprises means for connecting said first signalgenerating means to the anode of said LASCR whereby to render said LASCRnonconductive in response to said first control signal.

10. An annunciator circuit for use with a photographic circuit, saidphotographic circuit including a first signal generating means forgenerating a first control signal, a second signal generating means forgenerating a second control signal, a light producing means responsiveto said first control signal for initiating the operation of said lightproducing means whereby light is emitted therefrom, and a lightquenching means responsive to said second control signal for initiatingthe operation of said light quenching means whereby said emitted lightis effectively terminated, said annunciator circuit comprising:

an annunciator indicator selectively operable between a first and asecond condition;

a control member serially connected in an energization circuit with saidannunciator indicator, said control member being responsive to saidsecond control signal to effect a closure of said energization circuitthereby activating said annunciator indicator from said first conditionto said second condition; and

means associated with said energization circuit for resetting saidannunciator indicator to said first condition.

11. The annunciator circuit as set forth in claim 10 wherein said meansassociated with said energization circuit is responsive to said firstcontrol signal for resetting said annunciator indicator to said firstcondition.

12. The annunciator circuit as set forth in claim 11 wherein saidcontrol member comprises a silicon controlled rectifier (SCR) having itsanode-cathode path serially connected in said energization circuit, andmeans for connecting the gate electrode thereof to said second signalgenerating means whereby to render said SCR conductive in response tosaid second control signal.

13. The annunciator circuit as set forth in claim 12 wherein said meansassociated with said energization circuit comprises a capacitorconnecting said anode of said SCR with said first signal generatingmeans.

14. The annunciator circuit as set forth in claim 10 wherein said meansassociated with said energization circuit comprises a selectivelyoperable switching means.

15. A photographic apparatus comprising:

a first control signal generating means selectively operable forgenerating a first control signal:

a light producing means operative in response to said first controlsignal for providing light to illuminate a scene;

a second control signal generating means arranged to receive light fromsaid scene, said second control signal generating means being operativeto generate a second control signal upon receipt thereby of apredetermined amount of light from said scene;

light quenching means operative in response to said second controlsignal for effectively terminating said light provided by said lightproducing means;

an annunciator indicator selectively operable between a first and asecond condition;

a control member serially connected in an energization circuit with saidannunciator indicator, said control member being responsive to a signalindicative of a generation of said second control signal to effect aclosure of said energization circuit thereby activating said annunciatorindicator from said first condition to said second condition; and

means associated with said energization circuit for resetting saidannunciator indicator to said first condition.

16. The photographic apparatus as set forth in claim 15 wherein saidsignal indicative of a generation of said second control signal is saidsecond control signal, said control member comprising a siliconcontrolled rectifier (SCR) having its anode-cathode path seriallyconl060ll 0631 nected in said energization circuit with said annunciatorindicator, and means for applying said second control signal to the gateterminal of said SCR.

17. The photographic apparatus as set forth in claim 16 wherein saidmeans associated with said energization circuit comprising a selectivelyoperable switching means.

18. The photographic apparatus as set forth in claim 16 wherein saidmeans associated with said energization circuit is responsive to saidfirst control signal for resetting said annunciator indicator to saidfirst condition.

19. The photographic apparatus as set forth in claim 18 wherein saidmeans associated with said energization circuit comprises a capacitorconnecting said anode of said SCR with said first signal generatingmeans.

20. The photographic apparatus as set forth in claim wherein saidquenching means generates an incidental light during an operationthereof and said signal indicative of a generation of said secondcontrol signal is said incidental light, said control member comprisinga light activated silicon controlled rectifier (LASCR) having itsanode-cathode path serially connected in said energization circuit withsaid annunciator indicator, said LASCR being arranged in proximity tosaid light quenching means, said LASCR being rendered conductive, inresponse to said incidental light.

21. The photographic apparatus set forth in claim 20 wherein said meansassociated with said energization circuit comprises a selectivelyoperable switching means.

22. The photographic apparatus as set forth in claim 20 wherein saidmeans associated with said energization circuit is responsive to saidfirst control signal for resetting said annunciator indicator to saidfirst condition.

23. The photographic apparatus as set forth in claim 22 wherein saidmeans associated with said energization circuit comprises a capacitorconnecting said anode of ,said LASCR with said first signal generatingmeans. f'

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l060ll 0632

1. An annunciator circuit for use with a photographic circuit, saidphotographic circuit including a first signal generating means forgenerating a first control signal, a second signal generating means forgenerating a second control signal, a light producing means responsiveto said first control signal for initiating the operation of said lightproducing means whereby light is emitted therefrom, and a lightquenching means responsive to said second control signal for initiatingthe operation of said light quenching means whereby said emitted lightis effectively terminated, said annunciator circuit comprising: a signalresponsive annunciator indicator, a control member serially connected inan energization circuit with said annunciator indicator, said controlmember being responsive to said second control signal to effect aclosure of said energization circuit, thereby activating saidannunciator indicator, and selectively operable means for subsequentlyinterrupting said energization circuit.
 2. The invention as set forth inclaim 1 wherein said control member is a light activated siliconcontrolled rectifier (LASCR), having its anode-cathode path seriallyconnected in said annunciator circuit, said LASCR being arranged inproximity ti said light quenching means whereby to render said LASCRconductive in response to light given off during an operation of saidlight quenching means.
 3. The invention as set forth in claim 1 whereinsaid control member comprises a silicon controlled rectifier (SCR)having its anode-cathode path serially connected in said annunciaTorcircuit and means for connecting the gate electrode thereof to saidsecond signal generating means whereby to render said SCR conductive inresponse to said second control signal.
 4. The invention as set forth inclaim 3 wherein said annunciator indicator is a lamp member.
 5. Theinvention as set forth in claim 3 wherein said selectively operablemeans is a manually operated switch means serially connected in saidenergization circuit, a momentary selective operation of whichinterrupts said energization circuit, rendering said SCR nonconductive.6. The invention as set forth in claim 3 wherein said selectivelyoperable means comprises means for connecting said first signalgenerating means to the anode of said SCR whereby to render said SCRnonconductive in response to said first control signal.
 7. The inventionas set forth in claim 2 wherein said annunciator indicator is a lampmember.
 8. The invention as set forth in claim 2 wherein saidselectively operable means is a manually operated switch means seriallyconnected in said energization circuit, a momentary selective operationof which interrupts said energization circuit, rendering said SCRnonconductive.
 9. The invention as set forth in claim 2 wherein saidselectively operable means comprises means for connecting said firstsignal generating means to the anode of said LASCR whereby to rendersaid LASCR nonconductive in response to said first control signal. 10.An annunciator circuit for use with a photographic circuit, saidphotographic circuit including a first signal generating means forgenerating a first control signal, a second signal generating means forgenerating a second control signal, a light producing means responsiveto said first control signal for initiating the operation of said lightproducing means whereby light is emitted therefrom, and a lightquenching means responsive to said second control signal for initiatingthe operation of said light quenching means whereby said emitted lightis effectively terminated, said annunciator circuit comprising: anannunciator indicator selectively operable between a first and a secondcondition; a control member serially connected in an energizationcircuit with said annunciator indicator, said control member beingresponsive to said second control signal to effect a closure of saidenergization circuit thereby activating said annunciator indicator fromsaid first condition to said second condition; and means associated withsaid energization circuit for resetting said annunciator indicator tosaid first condition.
 11. The annunciator circuit as set forth in claim10 wherein said means associated with said energization circuit isresponsive to said first control signal for resetting said annunciatorindicator to said first condition.
 12. The annunciator circuit as setforth in claim 11 wherein said control member comprises a siliconcontrolled rectifier (SCR) having its anode-cathode path seriallyconnected in said energization circuit, and means for connecting thegate electrode thereof to said second signal generating means whereby torender said SCR conductive in response to said second control signal.13. The annunciator circuit as set forth in claim 12 wherein said meansassociated with said energization circuit comprises a capacitorconnecting said anode of said SCR with said first signal generatingmeans.
 14. The annunciator circuit as set forth in claim 10 wherein saidmeans associated with said energization circuit comprises a selectivelyoperable switching means.
 15. A photographic apparatus comprising: afirst control signal generating means selectively operable forgenerating a first control signal: a light producing means operative inresponse to said first control signal for providing light to illuminatea scene; a second control signal generating means arranged to receivelight from said scene, said second control signal generating means beingoperative to generate a secOnd control signal upon receipt thereby of apredetermined amount of light from said scene; light quenching meansoperative in response to said second control signal for effectivelyterminating said light provided by said light producing means; anannunciator indicator selectively operable between a first and a secondcondition; a control member serially connected in an energizationcircuit with said annunciator indicator, said control member beingresponsive to a signal indicative of a generation of said second controlsignal to effect a closure of said energization circuit therebyactivating said annunciator indicator from said first condition to saidsecond condition; and means associated with said energization circuitfor resetting said annunciator indicator to said first condition. 16.The photographic apparatus as set forth in claim 15 wherein said signalindicative of a generation of said second control signal is said secondcontrol signal, said control member comprising a silicon controlledrectifier (SCR) having its anode-cathode path serially connected in saidenergization circuit with said annunciator indicator, and means forapplying said second control signal to the gate terminal of said SCR.17. The photographic apparatus as set forth in claim 16 wherein saidmeans associated with said energization circuit comprising a selectivelyoperable switching means.
 18. The photographic apparatus as set forth inclaim 16 wherein said means associated with said energization circuit isresponsive to said first control signal for resetting said annunciatorindicator to said first condition.
 19. The photographic apparatus as setforth in claim 18 wherein said means associated with said energizationcircuit comprises a capacitor connecting said anode of said SCR withsaid first signal generating means.
 20. The photographic apparatus asset forth in claim 15 wherein said quenching means generates anincidental light during an operation thereof and said signal indicativeof a generation of said second control signal is said incidental light,said control member comprising a light activated silicon controlledrectifier (LASCR) having its anode-cathode path serially connected insaid energization circuit with said annunciator indicator, said LASCRbeing arranged in proximity to said light quenching means, said LASCRbeing rendered conductive, in response to said incidental light.
 21. Thephotographic apparatus set forth in claim 20 wherein said meansassociated with said energization circuit comprises a selectivelyoperable switching means.
 22. The photographic apparatus as set forth inclaim 20 wherein said means associated with said energization circuit isresponsive to said first control signal for resetting said annunciatorindicator to said first condition.
 23. The photographic apparatus as setforth in claim 22 wherein said means associated with said energizationcircuit comprises a capacitor connecting said anode of said LASCR withsaid first signal generating means.